package TestDemo;

public class MyLinkedList {

    static class ListNode{
        public int val;
        public ListNode prev;
        public ListNode next;

        public ListNode(){

        }

        public ListNode(int val){
            this.val = val;
        }
    }

    public ListNode head;
    public ListNode last;

    //头插法
    public void addFirst(int data){
        ListNode node = new ListNode(data);
        if (head == null){
            head = node;
            last = node;
        } else {
            node.next = head;
            head.prev = node;
            head = node;
        }
    }
    //尾插法
    public void addLast(int data){
        ListNode node = new ListNode(data);
        if (head == null){
            head = node;
            last = node;
        } else {
            last.next = node;
            node.prev = last;
            last = node;
        }
    }
    private boolean checkAddIndex(int index){
        return index < 0 || index > this.size();
    }
    private ListNode searchIndex(int index){
        ListNode cur = head;
        while (index > 0){
            cur = cur.next;
            index--;
        }
        return cur;
    }
    //任意位置插入,第一个数据节点为0号下标
    public void addIndex(int index,int data){
        if (checkAddIndex(index)){
            throw new AddIndexException("插入下标不合法");
        }
        if (index == 0){
            addFirst(data);
            return;
        }
        if (index == this.size()){
            addLast(data);
            return;
        }
        ListNode node = new ListNode(data);
        ListNode cur = searchIndex(index);

        node.prev = cur.prev;
        node.next = cur;
        cur.prev.next = node;
        cur.prev = node;
    }
    //查找是否包含关键字key是否在单链表当中
    public boolean contains(int key){
        ListNode cur = head;
        while (cur != null){
            if (cur.val == key){
                return true;
            }
            cur = cur.next;
        }
        return false;
    }
    //删除第一次出现关键字为key的节点
    public void remove(int key){
        ListNode cur = head;
        while (cur != null){
            if (cur.val == key){
                if (cur == head){
                    head = head.next;
                    if(head != null){
                        head.prev = null;
                    }
                } else if (cur == last){
                    last = last.prev;
                    last.next = null;
                } else {
                    cur.prev.next = cur.next;
                    cur.next.prev = cur.prev;
                }
                return;
            } else {
                cur = cur.next;
            }
        }
    }
    //删除所有值为key的节点
    /*public void removeAllKey(int key){
        ListNode cur = head;
        while (cur != null && cur.next != null){
            if (cur.next.val == key){
                if (cur.next == last){
                    last = last.prev;
                }
                cur.next = cur.next.next;
                if (cur.next != null){
                    cur.next.prev = cur;
                }
            } else {
                cur = cur.next;
            }
        }
        if (head.val == key){
            head = head.next;
            if (head != null){
                head.prev = null;
            }
        }
    }*/
    public void removeAllKey(int key){
        ListNode cur = head;
        while (cur != null){
            if (cur.val == key){
                if (cur == head){
                    head = head.next;
                    if(head != null){
                        head.prev = null;
                    }
                } else if (cur == last){
                    last = last.prev;
                    last.next = null;
                } else {
                    cur.prev.next = cur.next;
                    cur.next.prev = cur.prev;
                }
            }
            cur = cur.next;
        }
    }
    //得到单链表的长度
    public int size(){
        int n = 0;
        ListNode cur = head;
        while (cur != null){
            cur = cur.next;
            n++;
        }
        return n;
    }
    public void display(){
        ListNode cur = head;
        while (cur != null){
            System.out.print(cur.val+" ");
            cur = cur.next;
        }
        System.out.println();
    }
    public void clear(){
        ListNode cur = head;
        head = null;
        last = null;
        while (cur != null){
            ListNode curNext = cur.next;
            cur.prev = null;
            cur.next = null;
            cur = curNext;
        }
    }
}
